The present invention relates to catheters of any type meant for insertion through a body lumen such as vasculature. In particular, the present invention can effectively transmit torque in a desired manner along a catheter or other device for a body lumen having high profile.
In the last several years the field of minimally invasive surgery has grown exponentially. In particular, catheterization procedures such as angioplasty (including Percutaneous Transluminal Coronary Angioplasty) have become widely accepted norms. Even more complex procedures such as the placement of aneurysm grafts are accomplished by way of catheterization.
Due to the increased popularity of minimally invasive catheterization procedures, catheters have become more complex in order to accommodate additional catheter features needed for more complex procedures. Additional catheter features often result in catheters which are relatively large in diameter (i.e. high profile) and thus more susceptible to torque from a body lumen, such as vasculature, as the catheter is inserted through the body lumen.
One example of a complex catheter is the angioplasty catheter. Angioplasty is performed with an angioplasty catheter having an inflatable balloon at its distal end. The angioplasty catheter may be equipped with multiple lumen for inflation, deflation, guidewire access, visualization dye access, and for other purposes. The lumen will generally be located through a catheter shaft. The shaft will be of a sufficient profile to accommodate the various lumen. Such multi-lumen catheters are relatively large and stiff and therefore subject the associated flexible inflatable balloon to a considerable amount of torque upon insertion through a body lumen, in this case vasculature.
In order to insert a catheter such as the angioplasty catheter to a desired vessel location, the guidewire will first be inserted and steered to the site of a stenosis. Subsequently, the angioplasty catheter is inserted over the guidewire. The angioplasty catheter is steered through vasculature to the site of the stenosis with the object of placing the deflated balloon across the stenosis so that it may then be inflated to compress the stenosis against vessel walls.
Unfortunately, vasculature is often quite tortuous and of limited diameter. As the angioplasty catheter tightly forces its way through the vasculature, it is Subjected to vessel walls which act to wind and distort the angioplasty catheter as it makes various turns there through. The inflatable balloon, having more flexible walls than other portions of the angioplasty catheter, will distort and absorb the torque imposed by the tortuous vasculature. By the time the inflatable balloon reaches its destination it may be twisted and creased. This distortion will hamper the effectiveness of the angioplasty compression when the inflatable balloon is later inflated.
A similarly complex catheter procedure involves the placement of an aneurysm graft within an abdominal aneurysm. Placement of an aneurysm graft will involve an intricate delivery system, referred to here as an aneurysm graft catheter. The aneurysm graft catheter is constructed similarly to the angioplasty catheter with a balloon near its distal end. However, the aneurysm graft catheter is even larger and more complex. Proximal of the balloon, the catheter is equipped with additional obtrusive features such as a jacket guard. The jacket guard is proximal to the superior end of a capsule which houses an aneurysm graft. The balloon must be of sufficient size to aid in the deployment of the aneurysm graft from the capsule within a bifurcated aneurysm. The size of the balloon and the presence of a large diameter capsule housing an aneurysm graft increases the amount of torque which is endured by the catheter as it is forced through a tortuous vessel to the site of an aneurysm. As a result, the balloon of the aneurysm graft catheter is subjected to a significant amount of torque and again susceptible to distortion and creasing in reaching its destination.
As indicated in both of the above catheter procedure examples, torque control is vital to effective catheter placement and use. This is especially true where balloon or other flexible catheter features are present which are subject to torque effects. However, in addition to torque control, the catheter may display a degree of flexibility and be limited in size and stiffness in order to prevent damage to vasculature as the catheter is inserted there through. Unfortunately, more flexibility exhibited by the catheter generally equates to less torque control. Therefore what is needed is a catheter having able to overcome such torque problems and having advantages over prior art catheters.
The present invention provides a catheter. The catheter is equipped with a torque absorbing bearing disposed about a shaft of the catheter near a distal portion of a flexible region of the catheter. The catheter may be equipped with a plurality of torque absorbing bearings. The plurality includes a proximal torque absorbing bearing immediately distal of the flexible region.
A method of catheterization is also provided. A catheter having a torque absorbing bearing may be inserted through a tortuous body lumen.
A method of manufacturing a torque absorbing catheter is also provided. An embodiment is described in which a catheter shaft is molded and a torque absorbing bearing placed about the shaft. A bearing ring stop is placed adjacent the torque absorbing bearing.